Engine/Transmission (1998.5 - 2002) Stops at 90mph?????

[BIGDIG]

Why is it that as soon as I hit 90mph it feels like the truck hits cruise control and stays there,can't get it over 90??????

 

[Billy Diesel]

What are your RPM's at?



The 4:10 gears might be putting you close to the rev limiter depending on tire size.

 

[BIGDIG]

RPM is around 3,never really took a close look but I know its not near 4,000. Just seems like your picking up speed and when it hits 90 you can feel what kinda feels like cruise control kicking down when you tap the brake or shut it off..... I dun know!!!!!!

 

[BIGDIG]

oh and the tires are stock... .

 

[JaMan]

With 3. 55's and a ez and 275's mine will do 117mph. The mega cannon accounted for a 7-8mph gain. Stock tires.

 

[ToolManTimTaylor]

you are hitting the SPEED LIMITER (3500 series)

On a manual I have no idea how to kill it.

 

[ToolManTimTaylor]

Plus being stock shee's Juuuust about running out of steam (Get a Box and you will actualy FEEL it defuel)

 

[Billy Diesel]

There is a speed limiter on the 3500, but not the 2500??? Another one of those nice quirks that DC builds into our trucks...

 

[duaneparks]

Speed limiters are on both 2500 and 3500's. Mine too runs out of steam at 117, but I'm outta revs anyway.



Your 4. 10 gear is why you're hitting the limiter at 90. Mine, with the 3. 55's hits the same limiter, but because of the gearing difference the truck is actually travelling faster.



Did that help? Heck, I confused myself.



Duane

 

[Thob]

Put mine to the test this past weekend topped out at 110!

 

[K_Arts]

Originally posted by ToolManTimTaylor

On a manual I have no idea how to kill it.

I'd have to research it to find you the exact answer, but there was a post on here a while ago from Marco, saying that there was a wire on your ECM that you can clip to bypass the speed limiter.



Let me see what I can come up with.



Kev

 

[BIGDIG]

K_Arts-that would be cool,thanks

Duaneparks-yes that helped. It makes sense

Toolman-WHO ASKED YOU ANYWAYS,SAW/HEARD ENOUGH OF YOU SATERDAY!!!!!! kidding,I'm planning on seeing Scott thursday morning to get THE BOX

just what would happen if I snipped that wire?would I have to keep a close eye on the tack?

 

[K_Arts]

Ok... here you go buddy.



Bypassing the Speed limiter





Stated by KLockliear - White/orange wire going to your PCM, pin #27.



I hope this helps



Kev

 

[Marco]

Confusion

Well guys we have a little confusion here.



One thing is the Rev limiter of the engine, another thing is the speed limiter.

OK, both limit the top speed of the trucks in some way but that's all they share.



There are some trucks that actually have an speed limiter, others don't. Sorry I don't know exactly which year/model has the speed limiter, I'm sure someone here knows and will enlighten us.



IF the truck has an speed limiter then it has an White/Orange wire on cavity?? ( Can't remember have to look it up) of the ECM.

Cut that wire and splice an On/Off switch into it. Once at high speed flip the switch and bye-bye speed limiter.



Another thing is the rev limiter of the ECM for engine "protection".

The rev's are limited to about 3500 for partial load and 3200 for full load ( high speed ).

Since the 4. 10's never really load the engine when the truck is empty, what they loose in speed due to the shorter gears they gain it back because the engine will rev higher.



Clear as mud? Sorry dunno how to explain it better...





Marco

 

[K_Arts]

Very good point Marco... thanks for bring that up.



So how have ya been buddy? Long time no hear.



Kev

 

[Marco]

Fast!

Kev,

you've been faster than me! You owe ME a beer or two...



Thanks white/orange cavity #27.

Great!



Marco

 

[BIGDIG]

So from the sounds of that last post I should just leave it alone!!!!and live with my choice of 4:10s

 

[K_Arts]

BigDig. . the question is this. When you top out at 90. What are you RPM's? Are you in the 3200 range? If so, then it is a Rev limiter that is causing your problem.



With my truck at 90 in 4th gear, I'm still in the high 2000 range.



Marco... don't worry, all the beer's on me when you come out!!! LOL

 

[Marco]

BIGDIG, do you have or not the white/orange wire?



What about taller tires?:--)



Marco

 

[Marco]

BigDig. . the question is this. When you top out at 90. What are you RPM's? Are you in the 3200 range?



Nope Kev the 4. 10's should rev to 3. 5K at full speed.



Marco